Toss together tomatoes, onion, lettuce, and radishes; place in the refrigerator to chill. Use a mortar and pestle to mash the garlic with the salt and pepper. Pour the olive oil, vinegar, and lime juice in a small bowl. Add the crushed garlic and whisk together thoroughly. You can also use a blender to emulsify the oil and liquids.

Just before serving, gradually add the dressing, a little at a time, while you toss the salad with a large salad fork. Add just enough dressing to cover and salad - more or less to your own taste.